1. Field of the Invention
The present invention generally relates to a wireless communication system. More particularly, the present invention relates to a wireless communication base station sharing apparatus.
2. Description of the Related Art
As illustrated in FIGS. 1A, 1B and 1C, a plurality of service providers generally provide services through independent Base Stations (BSs) 10 and 12 in cellular, CDMA, PCS and GSM mobile communication systems and other wireless communication systems.
The resulting redundant investment in installation of individual BSs and unnecessary existence of too many BSs in an adjacent area lead to signal quality degradation due to mutual interference between the BSs.
It has occurred recently that one service provider merges other service providers and thus needs to provide services by integrating the frequency bands of the other service providers.
In this case, a need exists for unifying the existing system with the added systems to reduce cost.
One service provider may be assigned different frequencies in different areas in overseas countries. He must deploy BS systems operating in different frequency bands locally.
To overcome this problem, techniques for sharing a BS have been developed. One of the techniques is to share a BS antenna and a feeder cable by use of a new quadroplexer 132 covering the frequency bands of an existing BS system, for example, a system 10 (system A) and a sub-BS system, for example, a system 12 (system B), as illustrated in FIG. 1C.
This technique requires fabrication of such a quadroplexer as allows two systems to share an antenna and a feeder cable.
As described above, a new quadroplexer should be fabricated or a filter should be replaced or tuned in order to share an antenna and a feeder cable between an existing main BS system and an added sub-BS system. Therefore, much cost is incurred, including filter replacement cost and personnel expenses.